Apparatus for gas filling electric lamps



APPARATUS FOR GAS FILLING ELECTRIC LAMPS Filed June 1, 1959 I I J;- "r4.42

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nited States atenttlfice 3,028,712 APPARATUS FOR GAS FILLING ELEQTRICLAMPS John Flaws, J12, East Cleveland, and Ray 0. Dunbar,

Willonghby, Ohio, assignors to General Electric Company, a corporationof New York Filed June 1, 1959, Ser. No. 817,236 2 Claims. (Cl. 53-88)Our invention relates to a method and apparatus for flushing and gasfilling electric lamps.

The present invention is particularly concerned with gas fillingelectric incandescent lamps of the common so-called tipless typecomprising a glass bulb having a re-entrant glass stem tube sealed tothe end thereof and a glass exhaust tube within said stem tube andextending therefrom beyond the end of the bulb, and wherein portions ofthe said stem and exhaust tubes are fused and pinched together and anaperture or orifice is blown laterally from the exhaust tube through thefused mass of glass to afford communication with the interior of thebulb.

In accordance with present conventional practice, the lamps areassembled by sealing the mount structure, including the assembly of thestem and exhaust tubes and associated lead-in wires and filament, on acombination sealing and exhaust machine. After sealing, the lamps aretransferred to exhaust ports on the machine where they are exhausted ofair and flushed with nitrogen gas in a series of cycles which may occureleven times, after which they are filled with a final atmosphere,usually consisting of a mixture of 88% argon and the balance nitrogen,followed by sealing off the exhaust tube. This operation involves aconsiderable investment in equipment since the machine includes a rotaryvalve, manifolds, glass traps, compression rubbers and chucks, and isprovided with a source of vacuum that is external to the machine. Inorder to perform properly under vacuum, the rotary valve must belubricated and when the oil used for lubrication is exposed to vacuumthere is a likelihood that the flushing gas, when passing back and forththrough the system, will pick up hydrocarbons evaporated from the oiland carry them to the rest of the vacuum system and into the lamps.

It is an object of our invention to avoid the disadvantages of the priorart process and equipment by dispensing with the exhaust operation andemploying a flushing process wherein the air is displaced from the lampby an inert gas and the lamp is then sealed to retain the gas as thepermanent atmosphere. It is a further object to provide a method andapparatus which may be employed to flush and fill lamps of the tiplesstype with no alteration or modification in the construction of the lamp.

In accordance with one aspect of our invention, a fine hollow needlehaving a curved end is inserted into the exhaust tube of the lamp tocause the said curved end to project through and slightly beyond theaforesaid aperture in the stem. A flow of compressed inert gas is thensupplied to the needle to be directed in a high velocity jet stream tothe bulb wall at an acute angle thereto so as to provide a turbulentflow of the gas along the surface of the bulb wall and across thesurfaces of the filament, lead wires and other internal elements wherebythe resultant scrubbing action assists in dislodging and removingsurface impurities on those parts. The gas is ultimately swept from theinterior of the bulb through the said aperture and out through theexhaust tube around the said needle. The etfect of the scrubbing actionof the gas flow is so beneficial and thorough as to produce lamps of aquality as good as or even surpassing that of lamps made on theconventional prior art equipment. Moreover, lamps of good quality may bemade immediately at the start of the operation, whereas conventionalapparatus must be run for a substantial period to clear awaycontaminations which have entered the exhaust system overnight, beforelamps of good quality can be made therefrom.

Further features and advantages of our invention will.

appear from the following detailed description and from the drawingwherein:

FIG. 1 is a somewhat diagrammatic plan view of a form of flushingapparatus comprising our invention;

FIG. 2 is a vertical section, partly broken away, of the machine turretshowing one of the heads and the gas distribution system;

FIG. 3 is a perspective view of the internal mount structure of a lampin assembled relationship with a flushing needle; and

FIG. 4 is a perspective view of a sealing or tipping off mechanism inassociation with one of the machine heads.

Referring to FIGS. 2 and 3, the lamp which is to be flushed and gasfilled is of the conventional tipless lYPe comprising a glass bulb 1having a re-entrant glass stem tube 2 sealed to the end thereof and aglass exhaust tube 3 within the stem tube and extending therefrom. Thestem and exhaust tubes are fused and pinched together to form a press orpinch portion 4, and an aperture 5 is blown laterally from the exhausttube 3 through the fused mass of glass at the pinch seal 4 to afiordcommunication with the interior of the bulb 1. The mount structure alsoincludes a pair of lead-in wire 6 which have portions thereof sealed inthe pinch 4 and which carry a coiled tungsten filament 7. A glass arbor8 also extends longitudinally from the pinch portion 4 and carries tiewires 9 for bracing the lead-in wires 6 and a-support wire 10 foradditional support for the filament.

The apparatus illustrated herein comprises a turret 11 mounted on avertical column or shaft 12 for rota-.

tion by a well-known indexing mechanism, and carries a plurality ofheads or ports 13 at its periphery. Each of the vertically disposedports 13 has a body portion 14 secured in a block 15 on turret 11 by itsthreaded lower end 16 and sealed by a seal ring 17. A hollow flushingneedle 18 extends upwardly through the bore of the port body 14. Securedto the end of the needle 18 is an enlarged tubular base member 19 whichhas its lower portion cut away to a semi-cylindrical shape and which issupported in a well or passage 20 in the block 15 and is sealed off by aseal ring 21 which is compressed by the lower end of the port body 16.The needle 18, which,

when the exhaust tube 3 of the lamp is threaded down over theneedle,'the said needle will frictionally engage the Walls of the tubein a manner tending to straighten out the needle at its bent portion 23,thereby causing the curved end 22 to snap out through the aperture 5 andproject a short distance therefrom, for example about 1 mm. After theexhaust tube 3 has been inserted over the needle 18 and into the portbody 14, it is preferably clamped tightly therein by rotating a threadedcap 24 to compress a rubber washer 25 around the exhaust tube.

The loading of the lamp into the head or port 13 is performed at stationA (FIG. 1) and, as the head is indexed to station B, a flow of flushinggas, preferably nitrogen, is supplied to the needle 18. When the bulb isloaded, it is in aheated condition from the preceding operation ofsealing the mount structure to the bulb. The gas issues from the curvedend 22 of the needle in a Patented Apr. 10, 19ez stream directedupwardly at an acute angle to the vertical bulb axis and impingingagainst the wall of the bulb 1 to create a turbulent flow of the gasalong the bulb wall, around the interior thereof, and past the internalelements in the bulb until it is expelled, along with the originalatmospheric air, through the aperture 5 and through the exhaust tube 3around the needle 18. The gas is vented from the lower end of theexhaust tube 3 by way of the bore of the port body 14, apertures 26 inthe port body, a well 27 in block and passage 28 in block 15. a

The nitrogen gas is supplied to the well at the base of needle 18through a passage 29 (FIG. 2) in block 15, passage 30 in the bodyportion 31 of a valve, axial passage 32 in valve stem 33, transverseopening 34 in stem 33, passage 35 in body 31 and conduit 36, when thespring-loaded valve stem 33 is depressed by a bell crank 37 which isconnected to a push rod 38 which is pushed in upon engagement with thehigh surface 39 of a stationary cam track 40 surrounding the path oftravel of the heads 13. The conduit 36 is supplied with nitrogen gasfrom a source of supply by Way of a conduit 41 and through a rotaryconnector or slip valve 42 at the axis of the turret 11 and which willbe described hereinafter.

The flushing with nitrogen continues as the lamp travels around its pathon the turret until it reaches station N (FIG. 1) when the valvecontrolling plunger 38 moves forward against a section 43 of the camtrack 40 of reduced height whereby the valve stem 33 (FIG. 2) is raisedby spring 44, the passage 35 is blocked, and a lateral aperture 45 instem 33 is in communication with a passage 46 and conduit 47 whichcarries to the needle 18 a supply of filling gas which may consist ofthe conventional mixture of argon and nitrogen and which is suppliedfrom a conduit 48 through the slip valve 42. The argon-nitrogen mixturecontinues to flow at a substantial pressure, to displace the nitrogengas in the lamp bulb 1, until the lamp leaves station 0, at which timethe argonnitrogen mixture flows at a reduced rate when the plunger 38leaves the cam surface 43 so that the valve stem 33 is raised to itsuppermost position to block both apertures 34 and 35 and permit theargon-nitrogen mixture to fiow from passage 46 through a constrictedpassage 49 under the lower end of valve stem 33 and into passage 30.

At station P the cap 24 on the port 14 is rotated in a direction tounscrew it and release the pressure on the washer 25, the lamp bulb israised to a height such that the upper end of the needle 18 is locatedbelow the end of the bulb, and the exhaust tube is heated and tipped offat a position between the end of the bulb and the upper end of theneedle. During this time, the low pressure flow of the argon-nitrogengas is maintained to prevent ingress of air into the bulb.

The raising of the bulb and the tipping off operations may be performedby mechanism of a known type operating in synchronism with the indexingof the turret 11. As illustrated in FIG. 4, the mechanism comprises asupporting holder or cradle 50 which, along with a pair of gas burners51, is carried at the end of an arm 52 which is mounted on a verticalrod 53. Upon arrival of a lamp at station P, the arm 52 is first swungto bring the cradle 50 under the lower end of the bulb 1 and is thenraised to carry the bulb upward by suitable cam means (not shown) actingon the rod 53. The burners 51 heat a portion of the exhaust tube 3 toplasticity to close it off and sever it. The lamp 1 is removed from thecradle, and the residue of the exhaust tube is removed from the head 13preparatory to loading another lamp into the head.

Referring to the rotary slip valve 42, it comprises a stationary capportion 54 and a cylindrical body portion 55 which are screw-threadedtogether with a graphite seal ring 56 therebetween, and which aresupported by bearings 57 on the upstanding cylindrical wall 58 of avalve ring member 59 on the turret 11. The argonnitrogen mixture flowsfrom conduit 48 through a passage defined by the axial bore 60 of thecap 54, a metal sleeve 61, a graphite seal ring 62 and the interior of atubular member 63 carried by the turret 11, from which it flows througha passage 64 to the conduit 47. The nitrogen gas fiows from conduit 41through a lateral passage 65 in cap 54, through the annular spacebetween sleeve 61 and the enlarged bore of cap 54, through a series oflongitudinal openings 66 in a graphite sleeve 67 located between sleeve61 and the enlarged bore of cap 54, and through the annular space 68between wall 58 and tube 63 to a passage 69 connecting with conduit 36.The sealing rings 62 and 67 are pressed against the upper ends of therotating tube 63 and wall 58 by respective springs 70 and 71.

In order to prevent a flow of gas in case a lamp bulb 1 should be absentfrom one of the ports 13, a valve stem 72 may be provided in the valvebody 31 to block the passage 30. The stem 72 may be rotated byengagement with an arm portion 73 at its upper end, either manually orby a known form of solenoid-actuated mechanism including a feeler orsensing member which detects the absence of a bulb from the port 13.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. In apparatus for gas filling an electric lamp bulb of the tiplesstype having a re-entrant glass stem tube and a glass exhaust tube withinsaid stern tube and extending thereform and wherein portions of saidstem and exhaust tubes are fused and pinched together and an aperture isblown laterally from the exhaust tube through the fused mass of glassatfording communication with the interior of the bulb, an elongatedflexible hollow needle having a curved end and being of substantiallysmaller diameter than said exhaust tube for insertion into the exhausttube with its curved end projecting through and slightly beyond saidaperture, the mouth of said curved end of the needle being cut oft in aplane parallel to the axis of the adjacent straight length of the needleso that its overall transverse dimension is sufiiciently small to fitwithin the said exhaust tube, said needle being slightly bentintermediate its length in the same direction as its curved end so as tofrictionally engage the walls of said exhaust tube at its bent portionand at its curved end in a manner tending to straighten out the needleat its bent portion during insertion into said exhaust tube whereby itssaid curved end snaps out through said aperture upon completion of theinsertion, and means for supplying a flow of compressed inert gas tosaid needle for directing a jet of the gas against the bulb wall andflushing the air from the interior of the bulb and expelling it throughthe exhaust tube around the said needle.

2. In apparatus for gas .filling an electric lamp bulb of the tiplesstype having a re-entrant glass stem tube and a glass exhaust tube withinsaid stem tube and extending therefrom and wherein portions of said stemand exhaust tubes are fused and pinched together and an aperture isblown laterally from the exhaust tube through the fused mass of glassaffording communication with the interior of the bulb, a turret, a headmounted at the periphery of said turret and adapted to be carriedthereby along a path of travel, said head comprising a port adapted toreceive the end of the exhaust tube of an upright lamp and havingtherein passages venting the interior of the port and the exhaust tubetherein, an elongated hollow needle extending upwardly through andbeyond said port and having a curved upper end, said needle being ofsubstantially smaller diameter than said exhaust tube and arranged toextend upwardly through an exhaust tube in said port with its curved endprojecting through and slightly beyond the said aperture, the mouth ofsaid curved end of the needle being cut off in a plane parallel to theaxis of the adjacent straight length of the needle so that its overalltransverse dimension is sufiiciently small to fit within the saidexhaust tube means to supply a flow of compressed inert gas to the lowerend of said needle during the travel of said head along its path toflush the air from the interior of the bulb and expel it through theexhaust tube around said needle, and tipping-off means adjacent the pathof travel of said head including means operable to engage the bulbtherein and raise it a distance suflicient to leave the upper end ofsaid needle at a point intermediate the length of said exhaust tube andheater means arranged to fuse and seal off the exhaust tube at a pointabove the upper end of said needle.

References Cited in the file of this patent UNITED STATES PATENTS PayneDec. 7, 1937 Smith July, 13, 19 43 Geiger Apr. 18, 1944 Geiger et a1.July 2, 1946 White Aug. 21, 1956 McCabe Feb. 24, 1959 Bowtell et a1. May10, 1960

